CM3-Home technical documentation Buy
The most popular use of 1-wire bus is to use the Dallas DS18B20 temperature sensors. The image below illustrates how to wire it on the screw terminals available on the CM3-Home board. It is possible to wire more than one sensor.
As depicted on the CM3-HOME schematic, the 1-wire data line is interfaced through a dedicated buffer in order to allow a more robust bus, therefore it doesn't require a pullup.
To use the 1-wire sensor port add this lines to config.txt file and reboot:
# Enable the 1-wire bus dtoverlay=w1-gpio,gpiopin=16
The sensor wired are automatically detected by the Linux Kernel and a new directory is created on the folder /sys/bus/w1/devices for each of them.
$ ls /sys/bus/w1/devices/ 28-000006c423d3
In this case a temperature sensor with id=28-000006c423d3 has been detected. To read the temperature value type:
$ cat /sys/bus/w1/devices/28-000006c423d3/w1_slave a4 01 4b 46 7f ff 0c 10 da : crc=da YES a4 01 4b 46 7f ff 0c 10 da t=26250